Thrombectomy device and method

ABSTRACT

A mechanical thrombectomy device, and methods of manufacturing and using the mechanical thrombectomy device, are described. The mechanical thrombectomy device includes several clot arrestors independently mounted on a support wire. The clot arrestors have expandable frames that are eccentrically supported on the support wire. The independently and eccentrically mounted clot arrestors are arranged to allow a clot to pass into, and be captured by, one of the expandable frames. Furthermore, the independently and eccentrically mounted clot arrestors deform independently of one another such that retraction of the mechanical thrombectomy device through tortuous vasculature can stretch one clot arrestor without stretching another one of the clot arrestors to allow the clot to be retained by the unstretched clot arrestors. Other embodiments are also described and claimed.

This application is a continuation-in-part of U.S. patent applicationSer. No. 17/192,786, filed Mar. 4, 2021, which is incorporated herein byreference in its entirety to provide continuity of disclosure.

BACKGROUND Field

The present disclosure relates to mechanical thrombectomy devices usedfor ischemic stroke treatments. More specifically, the presentdisclosure relates to mechanical thrombectomy devices used forneurovascular thrombectomy procedures.

Background Information

Several classes of devices exist for salvaging the brain of patientssuffering from acute ischemic stroke. Among the classes are mechanicalthrombectomy devices, which are used to remove thrombi from theneurovasculature to restore perfusion through an initially occludedartery. Mechanical thrombectomy devices that have been cleared for suchuse include coil retrievers, aspiration devices, and more recently,stent retriever devices.

Existing stent retriever devices are essentially self-expanding stentsthat can be deployed within a thrombus to push the thrombus aside and/orentangle the thrombus within struts of the stent. After mechanicallyintegrating with the thrombus, the stent and thrombus can be withdrawninto a delivery catheter and removed from the patient. Important factorsin the usability and performance of stent retriever devices includetheir visibility under fluoroscopy, their ability to capture or engage aclot, and their ability to retain the captured or engaged clot as thedevice is retracted through tortuous vasculature. Shortcomings in thesefactors can extend procedural times and reduce clinical success rates.

SUMMARY

Existing stent retriever devices provide suboptimal visibility, clotengagement, and/or clot retention. Most stent retriever devices todayare not easily visualized under fluoroscopy during a procedure becausetheir structures are insufficiently radiopaque. Furthermore, most stentretriever devices today utilize a unitary stent body that hinders clotcapture and engagement. For example, the unitary stent body can rollover and pass by a hard clot, thereby bouncing off of the clot ratherthan engaging or capturing the clot. Furthermore, the unitary stent bodycan stretch over its entire length when pulled around a bend in avasculature, causing a captured clot to become disengaged and lost asthe stent body is pulled around the bend.

A mechanical thrombectomy device is described below, which addresses theshortcomings of existing stent retriever devices described above. In anembodiment, the mechanical thrombectomy device includes several clotarrestors independently supported on a support wire. For example, thesupport wire can have a distal segment that has a smaller diameter, oris otherwise less stiff, than a proximal segment, and the clot arrestorscan be mounted on the distal segment. More particularly, each clotarrestor can include an expandable frame and a stem, and the stem cancouple the expandable frame to the support wire at a joint. The jointcan be a mechanical joint, such as a radiopaque marker band crimpedaround the support wire and the stem. Thus, the joints can be visibleunder fluoroscopy. Furthermore, the clot arrestors can be independentlysupported by the support wire at respective joints that are spacedlongitudinally along the support wire. As such, when a deforming load isapplied to one of the expandable frames, the deforming load is nottransmitted to another one of the expandable frames. This can allow, forexample, one expandable frame to stretch and lose apposition with avessel wall when being pulled around a bend in a blood vessel, withoutcausing the other expandable frames to stretch and lose apposition withthe vessel wall. The mechanical thrombectomy device can therefore moreeffectively capture and retrieve clots from tortuous anatomies.

The expandable frames of the several clot arrestors can be eccentricallysupported on the support wire. For example, the expandable frames can bearranged such that arrestor axes of the expandable frames are notaligned with a wire axis of the support wire when the clot arrestors aredeployed in free space. When the clot arrestors are deployed in theblood vessel, however, the expandable frames can appose the vessel walland be forced into a concentric relationship with the vessel wall.Accordingly, the arrestor axes can align with the central axis of theblood vessel, which can force the support wire radially outward towardthe vessel wall. The support wire can therefore extend through theexpandable frames offset from the central axis of the blood vessel,e.g., spiraling along the vessel wall, leaving a lumen of the bloodvessel and interior channels of the expandable frames open to receive aclot. The mechanical thrombectomy device can therefore more effectivelycapture hard clots that will roll into the interior channel to becaptured rather than rolling between the device and the vessel wall tobe lost downstream.

The expandable frames of the several clot arrestors can benon-concentrically supported on the support wire. For example, theexpandable frames can be arranged such that arrestor axes of theexpandable frames are not aligned with each other when the clotarrestors are deployed in free space. When the clot arrestors aredeployed in the blood vessel, however, the expandable frames can apposethe vessel wall and be forced into a concentric relationship with eachother. The expandable frames can resiliently press outward to attempt toreturn to the undeformed, free state. The outward pressure from theresilient frames can be applied to the vessel wall in differenttransverse directions, since the expandable frames are non-concentric inthe free state. Accordingly, the non-concentric expandable frames canincrease a distributed radial force around the vessel wall, which mayaid clot capture as the device is retracted through the blood vessel.

Capture of clots can be further enhanced by features of the mechanicalthrombectomy device, such as a filter disposed at a distal end of thedevice, or the openings between adjacent independently-supported clotarrestors. The filter can be formed from a self-expandable web or meshthat allows blood to pass distally, but captures clots. The openings canbe adjusted by changing the spacing of the joints, the expandable framegeometry, or other variables to provide ports that hard or soft clotscan pass through to be captured within the interior channel of themechanical thrombectomy device. A method of manufacturing the mechanicalthrombectomy device, and a method of using the mechanical thrombectomydevice to remove a clot from a blood vessel are also described below.

The mechanical thrombectomy device can include clot arrestors having asegmented structure. For example, a distalmost clot arrestor can have asegmented body that includes a proximal frame segment and a distal framesegment. The frame segments can be coupled at a hinge, such as aconnector between the frames. The frame segments can tilt about thehinge when an axial load is applied to the mechanical thrombectomydevice, e.g., during retraction within a blood vessel. Moreparticularly, during clot retrieval, the frame segments can be forcedinto a concentric relationship and may also tilt. The tilting action cancause the frame segments to press outward against soft clots lining thevessel wall. The tilting action can also cause the frame segments toseparate such that hard clots can enter into a lumen of the framesegments though a segment gap between the frame segments.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a plan view of a mechanical thrombectomy device, in accordancewith an embodiment;

FIG. 2 is a plan view of a distal portion of a mechanical thrombectomydevice having several clot arrestors, in accordance with an embodiment;

FIG. 3 is a perspective view of a distal portion of a mechanicalthrombectomy device having several clot arrestors, in accordance with anembodiment;

FIG. 4 is an end view of several clot arrestors deployed in free space,in accordance with an embodiment;

FIG. 5 is an end view of several clot arrestors deployed in a bloodvessel, in accordance with an embodiment;

FIG. 6 is a side pictorial view of several clot arrestors deployed infree space, in accordance with an embodiment;

FIG. 7 is a side pictorial view of several clot arrestors deployed in astraight blood vessel, in accordance with an embodiment;

FIG. 8 is a perspective view of a clot arrestor, in accordance with anembodiment;

FIG. 9 is a side view of a clot arrestor, in accordance with anembodiment;

FIG. 10 is a perspective view of a clot arrestor, in accordance with anembodiment;

FIG. 11 is a perspective view of a filter mounted on a clot arrestor, inaccordance with embodiment;

FIG. 12 is a pictorial view of a mechanical thrombectomy device deployedin a curved vessel, in accordance with embodiment;

FIG. 13 is a pictorial view of a mechanical thrombectomy device beingretracted around a bend in a tortuous blood vessel, in accordance withan embodiment;

FIG. 14 is a flowchart of a method of manufacturing a mechanicalthrombectomy device, in accordance with an embodiment;

FIG. 15 is a flowchart of a method of removing a clot from a bloodvessel using a mechanical thrombectomy device, in accordance with anembodiment;

FIG. 16 is a plan view of a distal portion of a mechanical thrombectomydevice having several clot arrestors, in accordance with an embodiment;

FIG. 17 is a pictorial view of a mechanical thrombectomy deviceincluding a support wire having one or more inflections, in accordancewith an embodiment;

FIG. 18 is a plan view of a distal portion of a mechanical thrombectomydevice having several clot arrestors deployed in free space, inaccordance with an embodiment;

FIG. 19 is a plan view of a distal portion of a mechanical thrombectomydevice having several clot arrestors deployed in a blood vessel, inaccordance with an embodiment;

FIG. 20 is a perspective view of a distalmost clot arrestor of amechanical thrombectomy device, in accordance with an embodiment;

FIG. 21 is a side pictorial view of several clot arrestors deployed in ablood vessel, in accordance with an embodiment;

FIG. 22 is a side pictorial view of several clot arrestors deployed in ablood vessel, in accordance with an embodiment;

FIG. 23 is a perspective view of a frame marker, in accordance with anembodiment; and

FIG. 24 is a plan view of a radiopaque coil mounted on a support wire ofa mechanical thrombectomy device, in accordance with an embodiment.

DETAILED DESCRIPTION

Embodiments describe a mechanical thrombectomy device having clotarrestors independently and eccentrically mounted on a support wire. Themechanical thrombectomy device can be used to treat acute ischemicstroke. The mechanical thrombectomy device may, however be used in otherapplications, such as removal of clots from other vessels.

In various embodiments, description is made with reference to thefigures. However, certain embodiments may be practiced without one ormore of these specific details, or in combination with other knownmethods and configurations. In the following description, numerousspecific details are set forth, such as specific configurations,dimensions, and processes, in order to provide a thorough understandingof the embodiments. In other instances, well-known processes andmanufacturing techniques have not been described in particular detail inorder to not unnecessarily obscure the description. Reference throughoutthis specification to “one embodiment,” “an embodiment,” or the like,means that a particular feature, structure, configuration, orcharacteristic described is included in at least one embodiment. Thus,the appearance of the phrase “one embodiment,” “an embodiment,” or thelike, in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, configurations, or characteristics maybe combined in any suitable manner in one or more embodiments.

The use of relative terms throughout the description may denote arelative position or direction. For example, “distal” may indicate afirst direction along a longitudinal axis of a support wire or clotarrestor. Similarly, “proximal” may indicate a second direction oppositeto the first direction. Such terms are provided to establish relativeframes of reference, however, and are not intended to limit the use ororientation of a mechanical thrombectomy device to a specificconfiguration described in the various embodiments below.

In an aspect, a mechanical thrombectomy device includes several clotarrestors mounted on a support wire. The clot arrestors areindependently mounted. More particularly, each clot arrestor includes anexpandable frame that is attached to the support wire independently fromthe expandable frames of the other clot arrestors. Whereas competitivedevices stretch significantly when pulled around a bend in a tortuousvessel, the segmented configuration of the mechanical thrombectomydevice allows the clot arrestors to act independently of each other.Accordingly, stretching one clot arrestor does not cause another clotarrestor to stretch significantly. As a result, when the mechanicalthrombectomy device is retracted around a bend, even though the clotarrestor at the bend may stretch and lose apposition with the vesselwall, the clot arrestors distal and proximal to the bend remainun-stretched and apposed to the vessel wall. Accordingly, should theclot arrestor at the bend lose engagement with the clot, the clot canmove into and be captured and retained by the other clot arrestors thatappose the vessel wall.

In an aspect, the clot arrestors of the mechanical thrombectomy deviceare eccentrically supported on the support wire. When the clot arrestorsare deployed into a blood vessel and become concentrically arrangedwithin the blood vessel, the support wire can be pushed off center andtherefore may extend through the expandable frames of clot arrestorsoffset from a central axis of the blood vessel. The eccentricconfiguration of the expandable frames and the non-central location ofthe support wire can allow a clot to pass into and be captured by theexpandable frames. Whereas unitary stent bodies of existing stentretriever devices may not allow capture of a clot (and instead allow theclot to roll between the body and the vessel wall while the device isretracted), the segmented clot arrestors of the mechanical thrombectomydevice allow the clot to enter into a gap between the clot arrestors andtherefore be captured by the clot arrestors.

In an aspect, the clot arrestors of the mechanical thrombectomy deviceare attached to the support wire by joints that are highly visible underfluoroscopy. For example, each joint that connects a clot arrestor tothe support wire can include a radiopaque marker. The radiopaque markersdefine specific locations along the support wire relative to the clotarrestors. Accordingly, the radiopaque markers promote visibility of thedevice, and provide cues to an operator to understand where a clot islocated relative to the clot arrestors.

Referring to FIG. 1, a plan view of a mechanical thrombectomy device isshown in accordance with an embodiment. A mechanical thrombectomy device100 is an endovascular tool that can be used to treat acute ischemicstroke. The mechanical thrombectomy device 100 includes a proximalcontrol region 102 used by an operator to advance, retract, and rotate adistal working region 104 of the device. More particularly, themechanical thrombectomy device 100 includes a support wire 106 that theoperator can push to advance the distal working region 104, pull toretract the distal working region 104, or twist to rotate the distalworking region 104. The mechanical thrombectomy device 100 can includeseveral clot arrestors 108 that can be advanced through and deployedfrom a microcatheter into a target anatomy. The clot arrestors 108, whendeployed within the target anatomy, can capture, catch, engage, ormechanically integrate with a clot. The arrested clot can be retrievedfrom a patient by pulling the support wire 106 to retract the clotarrestors 108 and the clot from the vasculature.

In an embodiment, the support wire 106 includes a proximal wire end 110and a distal wire end 112. The support wire 106 can extendlongitudinally from the proximal wire end 110 to the distal wire end 112along a wire axis. The support wire 106 can be a flexible elongated wireformed from a resilient material, such as stainless steel or asuperelastic nickel titanium alloy, and thus, the wire axis may have oneor more straight or curvilinear segments between the proximal wire end110 and the distal wire end 112. A length of the support wire 106 may beless than an overall length of the mechanical thrombectomy device 100.For example, the distal wire end 112 may be located distal to at leastone of the clot arrestors 108, and proximal to a distal end of at leastone of the clot arrestors 108. Accordingly, a distance from the proximalwire end 110 (at a proximal device end 114) to the distal wire end 112may be less than a distance from the proximal wire end 110 to a distaldevice end 116.

Referring to FIG. 2, a plan view of a distal portion of a mechanicalthrombectomy device having several clot arrestors is shown in accordancewith an embodiment. The clot arrestors are independently mounted on thesupport wire 106. More particularly, each clot arrestor 108 includes arespective expandable frame, and the respective expandable frames of theclot arrestors 108 are connected to the support wire 106 at respectivelocations. For example, a first clot arrestor 202 has a first expandableframe 204 and a first stem 206 that connects the first expandable frame204 to the support wire 106 at a first joint 208. The first joint 208can be at a first location 209 along the support wire 106. A second clotarrestor 210 has a second expandable frame 212 and a second stem 214that connects the second expandable frame 212 to the support wire 106 ata second joint 216. The second joint 216 can be at a second location 217along the support wire 106. The mechanical thrombectomy device 100 mayhave more than two clot arrestors 108. For example, a third clotarrestor 218 has a third expandable frame 220 and a third stem 222 thatconnects the third expandable frame 220 to the support wire 106 at athird joint 224. The third joint 224 can be at a third location 225along the support wire 106. The attachment points of the respective clotarrestors 108 can be longitudinally separated along the support wire106. For example, the first location 209, the second location 217, andthe third location 225 can be at different longitudinal locations on thesupport wire 106. Accordingly, the expandable frames of the clotarrestors 108 can be arranged in series in the longitudinal direction,and each expandable frame can be independently supported on the supportwire 106 relative to the other expandable frames.

The sequentially arranged clot arrestors 108 may have identical ordifferent structures. For example, in the embodiment shown in FIG. 2,the most proximal clot arrestor, i.e., the first clot arrestor 202, andthe middle clot arrestor, i.e., the second clot arrestor 210, areidentical in that the stems and joints of those expandable frames havethe same geometries. By contrast, the distalmost clot arrestor 108,i.e., the third clot arrestor 218, can have a geometry that differs fromthe first clot arrestor 202 and the second clot arrestor 210. Some ofthese geometrical differences are described below, but it will beappreciated that one difference can the presence of one or more struts230 extending distally from an expandable frame to support a filter 232at the distal device end 116. Accordingly, the independently supportedclot arrestors 108 can be sized and shaped to provide respective degreesof clot engagement, clot capture, flexibility, or any other performanceattribute.

Referring to FIG. 3, a perspective view of a distal portion of amechanical thrombectomy device having several clot arrestors is shown inaccordance with an embodiment. The support wire 106 that supports theclot arrestors 108 may have a proximal segment 302 and a distal segment304. The proximal segment 302 may extend over the proximal controlregion 102, proximal to the clot arrestors 108, and the distal segment304 may extend within the distal working region 104, through one or moreof clot arrestors 108.

The support wire 106 segments can be adapted to their purpose. Forexample, the proximal segment 302 may function primarily to transferaxial and rotational loads from the operator to the distal workingregion 104. Accordingly, the proximal segment 302 of the support wire106 may have a proximal diameter 306 suited to those functions. By wayof example, the proximal diameter 306 can be in a range of 0.010-inch to0.020-inch, e.g., 0.018-inch. By contrast, rather than functioningprimarily to transmit control forces, the distal segment 304 mayfunction primarily as a support for the clot arrestors 108. As such, thedistal segment 304 can have a distal diameter 308 that is less than theproximal diameter 306. For example, the distal diameter 308 can be in arange of 0.004-inch to 0.010-inch, e.g., 0.0045-inch. Accordingly, theproximal segment 302 of the support wire 106 can have a larger diameterthan the distal segment 304 of the support wire 106. The smallerdiameter of the distal segment 304 may serve several purposes. First,the smaller diameter can impart flexibility to the distal segment 304 ofthe support wire 106, allowing it to undulate and spiral along an innerdimension of the target anatomy and clot arrestors 108, as describedbelow. Second, the distal segment 304 extends through the clot arrestors108, and thus, the smaller diameter allows or a smaller packing ratiowhen the mechanical thrombectomy device 100 is being advanced through amicro catheter. The smaller packing ratio can allow the device to bedelivered more easily through the micro catheter to the target anatomy.

The structure of the support wire 106 described above may be achieved bya single wire. For example, a single wire can be ground or otherwisetapered at discrete locations between the proximal wire end 110 and thedistal wire end 112 to form the proximal segment 302 and the distalsegment 304. By way of example, a single wire may be 0.018-inch at theproximal wire end 110, and can taper distally over its length to havediameters of 0.010-inch, 0.006-inch, and 0.0045-inch at differentlocations along the wire length. The taper can be uniform, or introducedat discrete locations to form several wire segments having respectivediameters.

In an embodiment, the support wire 106 is made from several wiresegments joined together. For example, the proximal segment 302 may be afirst wire having a distal end at the first location 209. Similarly, thesupport wire 106 can include a second wire having a proximal end at thefirst location 209. The first wire can have a larger diameter than thesecond wire, as described above. The wire segments can be joinedtogether by a joint. For example, the first joint 208, which attachesthe first clot arrestor 202 to the support wire 106, can also join theends of the several wire segments to form a unitary support wire 106.

Each of the joints of the mechanical thrombectomy device 100 can beformed using a mechanical, thermal, or adhesive bond. For example, thefirst joint 208 can include a marker band that is mechanically crimpedaround the support wire 106 and the first stem 206 of the first clotarrestor 202 to attach the clot arrestor to the support wire 106. Themarker band can be a tubular sleeve formed from platinum-iridium,stainless steel, gold, tungsten, or another radiopaque material.Accordingly, the marker band can provide a radiopaque marker 310. Thefirst stem 206 can include a tail portion that is placed inside of themarker band adjacent to the support wire 106. When the marker band iscrimped, it can squeeze the support wire 106 and stem to secure the clotarrestor to the support wire 106. In an embodiment, an adhesive may beadded to further secure the marker band, the clot arrestor, and thesupport wire 106 to each other to form the first joint 208.

The joints may be formed in alternative manners. For example, any of thejoints between the clot arrestors and the support wire 106 can be formedusing a laser weld, solder, or brazed joint. The mechanical, thermal, oradhesive joints may provide a degree of radiopacity, and furthermore,may secure the radiopaque marker 310 to the support wire 106. Forexample, a tungsten rod may be bonded to the support wire 106 at thefirst location 209. Accordingly, the mechanical thrombectomy device 100includes radiopaque marker(s) at the joint(s) along the support wire106.

The radiopaque marker(s) make the device easier to visualize underfluoroscopy. The locations of the joints and radiopaque markers 310 canbe used as cues to an operator to understand relative placement betweenthe clot arrestors and clots within the target anatomy. For example, theradiopaque marker 310 at the first joint 208 can be proximal to thefirst expandable frame 204, and thus, the operator can retract themechanical thrombectomy device 100 to retract the first joint 208 past aclot to allow the clot to advance into an interior of the firstexpandable frame 204. Similarly, another radiopaque marker 310 can belocated at the second joint 216 at the second location 217 along thesupport wire 106. Thus, the operator can retract the mechanicalthrombectomy device 100 to retract the second joint 216 past the clot toallow the clot to advance into an interior of the second expandableframe 212. Likewise, another radiopaque marker 310 can be located at thethird joint 224 at the third location 225 along the support wire 106.Thus, the operator can retract the mechanical thrombectomy device 100 toretract the third joint 224 past the clot to allow the clot to advanceinto an interior of the third expandable frame 220.

The positioning of the radiopaque markers 310 proximal to the interiorsof the respective expandable frames can provide several benefits. First,as described above, the location provide clear feedback to the operatorof the relative location between a clot that is longitudinally alignedwith the marker and the interior of the respective expandable frames.Second, by locating the marker bands proximal to the expandable frames,rather than longitudinally coincident with the expandable frames, theframes can be reduced to an unexpanded state at locations distal to theradiopaque markers 310, and thus, without enclosing the markers. Moreparticularly, the radiopaque markers 310 do not add to a crimpeddiameter of the expandable frames because the joints are proximal to theexpandable frames. As a result, the relative location of the markers andthe expandable frames benefits a packing ratio (smaller unexpandedprofile) of the mechanical thrombectomy device 100 and contributes toimproved delivery of the device through a microcatheter.

Referring to FIG. 4, an end view of several clot arrestors deployed infree space is shown in accordance with an embodiment. Each of the clotarrestors 108, which are independently mounted on the support wire 106,have expandable frames that are eccentrically supported on the supportwire. The support wire 106 includes a wire axis 402 extendinglongitudinally through the support wire body. As described above, thewire axis 402 may have linear and curvilinear segments because thesupport wires is flexible. For modeling purposes, however, the wire axis402 may be shown as linear (FIG. 3), and thus, is represented as asingle point within the cross-sectional view of FIG. 4.

Each clot arrestor 108 can have an arrestor axis 404 that is radiallyoffset from the wire axis 402. As described below, the clot arrestors108 may be formed by laser-cutting a three-dimensional expandablestructure from a cylindrical tube, and thus, the expandable frames ofthe clot arrestors 108 can have circular cross-sectional profiles, asshown in FIG. 4. The centers of these profiles can define the respectivearrestor axes 404, which extend longitudinally through the clotarrestors 108. Given that the arrestor axes 404 are radially spaced fromthe wire axis 402, the clot arrestors 108 are eccentrically supported onthe support wire 106. More particularly, the stems of the clot arrestors108 can attach to the support wire 106 at the wire axis 402, but theexpandable frames are eccentrically supported about the support wire106.

In an embodiment, the eccentrically supported expandable frames areradially oriented about the wire axis 402. Each clot arrestor 108 canhave a respective radial plane that contains the wire axis 402 and arespective arrestor axis 404. For example, a first radial plane 406 canextend radially from the wire axis 402 through a first arrestor axis 408of the first clot arrestor 202. Similarly, a second radial plane 410 canextend radially from the wire axis 402 through a second arrestor axis412 of the second clot arrestor 210, and a third radial plane 414 canextend radially from the wire axis 402 through a third arrestor axis 416of the third clot arrestor 218. The radial planes can be angularlyoffset from each other about the support wire 106. For example, theradial planes can radiate in different directions from the wire axis 402such that the expandable frames are non-concentrically supported on thesupport wire 106 relative to each other. The non-concentric distributionof the expandable frames is evident from the arrestor axes beingnon-coincident when viewed in the distal direction.

The radial planes of the clot arrestors 108 may be distributed about thesupport wire 106 uniformly or non-uniformly. In the embodiment shown inFIG. 4, the radial planes are non-uniformly distributed about thesupport wire 106. More particularly, an angle between the first radialplane 406 and the second radial plane 410 in a counterclockwisedirection is approximately 60°, an angle between the second radial plane410 and the third radial plane 414 in the counterclockwise direction isapproximately 60°, and an angle between the third radial plane 414 andthe first radial plane 406 in the counterclockwise direction isapproximately 240°. Thus, the angles between adjacent clot arrestors 108are not equal, and the clot arrestors 108 are not uniformly orientedabout the support wire 106. By contrast, the radial planes may beuniformly distributed when the angles between all adjacent clotarrestors 108 are equal. In the generalized case, the angle betweenradial planes is 360° divided by the number of clot arrestors 108. Forexample, in the case of three clot arrestors 108, the expandable framesare uniformly distributed about the support wire 106 when the anglesbetween the first plane, the second plane, and the third plane are 120°.It will be appreciated then, that the non-uniform distribution is shownby way of example, and that the radial planes may be uniformlydistributed about the support wire 106 when the angles between theradial planes are equal.

Referring to FIG. 5, an end view of several clot arrestors deployed in ablood vessel is shown in accordance with an embodiment. The descriptionof eccentrically supported expandable frames provided above is made inreference to FIG. 4, which shows the clot arrestors 108 havingnon-coincident arrestor axes when the distal working region 104 isexpanded in free space, e.g., in a naturally expanded state with noexternal forces being applied to the expandable frames. FIG. 5illustrates the effect of deploying the independently and eccentricallysupported clot arrestors 108 into a blood vessel 502.

When the non-concentrically supported expandable frames are constrainedby a vessel wall 504 of the blood vessel 502, the vessel wall 504 willpush radially inward against the expandable frames to drive the clotarrestors 108 toward a concentrically supported orientation. Moreparticularly, given that the radial strength of the vessel wall 504 isgreater than the stiffness of the distal segment 304 of the support wire106, the support wire 106 will flex to allow the eccentrically supportedexpandable frames to tend toward a concentric configuration. In theillustrated example, the expandable frames are not completelyconcentric. This could be the case in practice, because the resilienceof the support wire 106 will act on each clot arrestor 108 individually,as a result of their independently supported configuration, to push theclot arrestors 108 in different directions relative to the wire axis402. Accordingly, in the exaggerated illustration of FIG. 5, when theplurality of clot arrestors 108 are deployed in the blood vessel 502,the expandable frames press against the vessel wall 504 in differenttransverse directions, as shown by force vectors 506.

Notably, the cross-sections of the first clot arrestor 202, the secondclot arrestor 210, and the third clot arrestor 218 shown in FIG. 5 areactually at different longitudinal locations that are overlaid on eachother. Accordingly, the cross-sections of the support wire 106 shown inFIG. 5 are at different longitudinal locations relative to each other.This realization illustrates that deployment of the clot arrestors 108into a confining space, such as the blood vessel 502, force the supportwire 106 into a non-linear shape in which the support wire 106 is notcentrally located within the space. More particularly, when the clotarrestors 108 are deployed in the blood vessel 502 with the expandableframes apposed to the vessel wall 504, the support wire 106 extendsthrough one or more of the expandable frames offset from a central axis510 of the blood vessel 502. This result of the independently andeccentrically supported clot arrestor 108 configuration is describedfurther below.

Referring to FIG. 6, a side pictorial view of several clot arrestorsdeployed in free space is shown in accordance with an embodiment. Asdescribed above, each clot arrestor 108 includes a respective stem 602coupling a respective expandable frame 604 to the support wire 106 at arespective joint 606. The stem 602, expandable frame 604, and joints 606can be individually labeled, e.g., first, second, and third, asdescribed above, however, for the purposes of FIGS. 6-7 those componentfeatures are labeled generally. In the natural state, the support wire106 can be linearly arranged, extending through one or more of theexpandable frames 604. For example, the support wire 106 can extendfully through the proximal and medial expandable frames 604, and canterminate proximal to a distal end of the distal expandable frame 604.The joints 606 are spaced longitudinally along the support wire 106 andthe stems 602 are separate from each other such that the expandableframes 604 are independently supported on the support wire 106.Furthermore, the expandable frames 604 are eccentrically supported onthe support wire 106, as evidenced by the arrestor axes 404 beingradially offset (vertically offset in the side view) from the wire axis402.

Referring to FIG. 7, a side pictorial view of several clot arrestorsdeployed in a straight blood vessel is shown in accordance with anembodiment. When the distal working region 104 is deployed in the bloodvessel 502, the vessel wall 504 applies a deforming load 702 to the clotarrestors 108. In this case, the deforming load 702 is a radial load,driving the arrestor axes into alignment in the radial direction. Thedeforming load 702 may also be an axial load (FIG. 13) that causesstretching of one or more of the expandable frames 604. In any case, asa result of the clot arrestors 108 being independently supported at thelongitudinally spaced joints 606, the deforming load 702 applied to oneof the expandable frames 604 is not transmitted to another one of theexpandable frames 604. Rather, the expandable frames 604 are deflectedindependently of each other. In the illustration, this is shown as theproximal and distal expandable frames 604 being driven downward whilethe medial expandable frame 604 is driven upward. The independentmovement of the expandable frames 604 brings the arrestor axes 404 intoalignment.

As the expandable frames 604 align within the vessel, the support wire106 is deflected into a non-linear shape. More particularly, theproximal segment 302 of the support wire 106 may remain linear, e.g.,straight, but given that the arrestor axes 404 are eccentrically locatedwith respect to the wire axis 402, as the arrestor axes 404 become morecentral, e.g., aligned with the central axis 510 of the blood vessel502, the distal segment 304 of the support wire 106 supporting theexpandable frames 604 may become non-linear, e.g., curved. Moreparticularly, the wire axis 402 can become off-center, e.g., forcedradially outward toward the vessel wall 504, and the support wire 106may therefore take on a curvilinear shape that is different than thelinear shape of the proximal segment 302.

In an embodiment, the support wire 106 extends through each clotarrestor 108 along an interior wall of the respective expandable frame604. For example, as shown in FIG. 5, the support wire 106 within eachexpandable frame 604 is located along the interior wall of theexpandable frame 604, circumferentially offset from the location thatthe primary force vector 506 is applied to the vessel wall 504. Thesupport wire 106 can undulate along the vessel wall 504. In the sideview of FIG. 7, this is evident from the curving path that the supportwire 106 takes upward and downward in the longitudinal direction. Theundulating path has peaks and valleys at which the support wire 106 isforced against the vessel wall 504 by the deforming loads 702. The peaksand valleys can coincide with the interior channel of the expandableframes 604, e.g., the support wire 106 can have a peak or a valley at aninterior wall of the expandable frames 604. In an embodiment, thesupport wire 106 presses against the interior wall of the expandableframe 604 when it is forced away from the central axis 510 of the bloodvessel 502.

In three dimensions, the undulating path of the support wire 106 may bea spiraling path. More particularly, given that the clot arrestors 108are non-concentrically arranged about the wire axis 402, as thedeforming loads 702 move the expandable frames 604 independently indifferent directions to force them into alignment with each other andthe vessel lumen, the connections to the support wire 106, e.g., therespective joints 606, will be forced in different directions as well.This can cause the support wire 106 at one joint 606 to be forcedagainst the blood vessel 502 at a first radial location, e.g., azero-degree location, another joint 606 to be forced against the bloodvessel 502 at a second radial location, e.g., a 120-degree location, andanother joint 606 to be forced against the blood vessel 502 at a thirdradial location, e.g., a 240-degree location. As the support wire 106extends longitudinally through the joints 606 at each of these radiallocations, it can take on a spiraling configuration. More particularly,the support wire 106 can spiral along the vessel wall 504 when theexpandable frames 604 and the respective joints 606 are apposed to thevessel wall 504. Accordingly, it will be appreciated that the supportwire 106 can undulate distally making contact with the vessel wall 504at one or more peaks or valleys, and that the support wire 106 canspiral distally making contact with the vessel wall 504 consistentlyover the length of the distal segment 304 of the support wire 106.

The undulating or spiraling support wire 106 provides severalperformance benefits. First, the offset of the support wire 106 from thevessel wall 504 causes the expandable frames 604 to press against thevessel with force vectors 506 in different directions. The support wire106 provides a reaction load to the deforming load 702 applied to theexpandable frames 604 by the vessel wall 504, and this reaction load isexperienced by the vessel wall 504 as the force vectors 506. When theclot arrestors 108 are deployed in the blood vessel 502, the supportwire 106 is forced away from the central axis 510 of the blood vessel502 in different directions, and thus, the reactive loads are directedopposite to those different directions. Accordingly, the expandableframes 604 can provide a higher radial force to the vessel wall 504 whendeployed in the vessel because the support wire 106 applies the forcevectors 506 that press against the vessel wall 504.

Another benefit of the undulating or spiraling support wire 106 is theclearance that it provides for the capture of thrombus. When the clotarrestors 108 are deployed in the blood vessel 502, the support wire 106is offset to the circumference of the expandable frame 604 and the bloodvessel 502, which allows the central lumen, e.g., the interior channelof the expandable frames 604, to remain fully open to the passage of aclot. Still referring to FIG. 7, when the expandable frames 604 areexpanded and apposed to the vessel wall 504, the support wire 106 runsalong the vessel wall 504 at different circumferential locations in eachexpandable frame 604. A gap 704 can exist between adjacent expandableframes 604, and that gap can provide an opening through which a clot canenter into a central lumen of the mechanical thrombectomy device 100.The central lumen can be the volume that is radially inward from thevessel wall 504 and the interior wall of the expandable frame 604. Itwill be appreciated that a centrally located support wire 106, e.g., asupport wire 106 that is aligned with a central axis 510 of the bloodvessel 502, could prevent entry of the clot into the central lumen bydeflecting the clot radially outward. The deflected clot could then rollbetween an outer surface of the expandable frames 604 and the vesselwall 504, and not be captured. By contrast, the circumferentially offsetsupport wire 106 leaves the central lumen unblocked, and maximizes thevolume in the central lumen to receive the clot. The clot then, ratherthan being deflected outward, is able to move fully into the centrallumen to be captured by the expandable frames 604 as they are retractedthrough the blood vessel 502.

In addition to having a circumferentially offset support wire 106 toclear the central lumen of the device to receive clots, the gaps 704between expandable frames 604 can also be controlled to enhance clotcapture. More particularly, the openings between a distal frame end 706of one expandable frame 604 and a proximal frame end 708 of an adjacentexpandable frame 604 act as channels or ports through which clots canenter the central lumen of the device. The gaps 704 may be sized toensure that clots, e.g., hard clots that roll between the expandableframes 604 and the vessel wall 504, will enter the gaps 704 when theybecome longitudinally aligned with the gaps 704. The distance betweenthe distal frame end 706 of one expandable frame 604 and the proximalframe end 708 of the adjacent expandable frame 604 can be in a range of10-20 mm, e.g., 15 mm, to accommodate most hard clots. It will beappreciated that the gap 704 may have a different length in thelongitudinal direction, however, depending on the range of clot sizesintended for capture.

In an embodiment, the gap 704 between one pair of expandable frames 604may be different than the gap 704 between another pair of expandableframes 604, in size or shape. For example, the length of the gap 704between the proximalmost and medial expandable frames 604 of FIG. 7 maybe different, e.g., less than, the length of the gap 704 between themedial and distalmost expandable frames 604 of FIG. 7. Similarly, thestructures of the expandable frames 604 may have different geometriessuch that the gap 704 between the proximalmost and medial expandableframes 604 of FIG. 7 is shaped differently than the gap 704 between themedial and distalmost expandable frames 604 of FIG. 7. The variation ingap length and/or shape can provide for the openings to be more or lessaccommodative to different clot types. For example, a shorter and widerproximal opening may be more accommodative to capturing hard clots and alonger and narrower distal opening may be more accommodative tocapturing soft clots.

Referring to FIG. 8, a perspective view of a clot arrestor is shown inaccordance with an embodiment. As described above, each clot arrestor108 can have expandable frame and stem portions. The expandable frameportion 604 includes the distal frame end 706 and the proximal frame end708. The frame ends can define openings into an interior channel 812 ofthe expandable frame 604, e.g., a proximal opening into a cylindricalinterior of the expandable frame 604 and a distal opening into thecylindrical interior. The expandable frame 604 can include at least onering of frame cells 802. The ring of frame cells 802 can be configuredto expand and collapse. Geometrically, the expandable frame 604 can besimilar to a stent. For example, the ring of frame cells 802 can includetwo or more cells linked to each other in a circumferential direction toform a cylindrical expandable structure having an “open” or “closed”cell pattern. The cell pattern includes one or more slots, struts, orlinks 820 to form an expandable structure having proximal and/or distalopening to arrest a clot. As with stents, the clot arrestor 108 can beformed by laser-cutting the cell pattern from metal tubing. For example,the expandable frame 604 can be a self-expanding structure formed from ashape memory alloy, e.g., nickel titanium tubing. Unlike stents,however, the radial force requirements of the expandable frame 604 maybe secondary to the structure shape, which should accommodate clotcapture rather than act as a scaffold to prop open an atheroscleroticlesion.

Also unlike stent scaffolds, the clot arrestor 108 can include the stem602 extending proximally from the expandable frame 604. Moreparticularly, the stem 602 can extend proximally from a proximal ringend 803 of the ring of frame cells 802 (at the proximal frame end 708)to a proximal stem end 804. Just as the distal frame end 706 can definea distalmost location or edge of the clot arrestor 108, so can theproximal stem end 804 define a proximalmost location of the clotarrestor 108. Neither the distalmost location nor the proximalmostlocation of the clot arrestor 108 is directly connected to an adjacentclot arrestor, and thus, the clot arrestor 108 is an independent bodyfreely suspended on the support wire 106.

In an embodiment, the stem 602 includes one or more branches extendingfrom the proximal stem end 804 to the proximal frame end 708. The stem602 could be a single, straight wire segment extending proximally fromthe expandable frame 604 to the joint 606 at the support wire 106, asmodeled in FIGS. 6-7. In an embodiment, however, the stem 602 includesseveral branches that extend between the joint 606 at the proximal stemend 804 and the proximal ring end 803 of the ring of frame cells 802.The branches can act as tails that trail the expandable frame 604 toconnect the ring of frame cells 802 to the support wire 106. The branchgeometry can transmit forces, e.g., pulling forces, to the expandableframes 604 during operation, and can contribute to clot capture.

With respect to pull force transmission, the branches can bifurcate onceor more between the proximal stem end 804 and the proximal frame end 708to form a structure that connects to each of the proximal ring ends 803.More particularly, the stem 602 can extend proximally from each proximalapex of the expandable ring structure, and thus, pull forces transmittedfrom the support wire 106 to the expandable frame 604 though the stembranches will be uniformly distributed around the proximal frame end708. The uniform distribution of pull force can reduce tilting of theexpandable frame 604 during device retrieval, and thus, may reducevessel injury and or clot loss.

Several of the branches of the stem 602 can define a mouth 810 to aninterior channel 812 of the expandable frame 604. For example, a pair ofbranches can bifurcate near the proximal stem end 804 and extenddistally toward the proximal ring end 803. At the proximal ring end 803,the pair of branches can continue along a proximal edge of the ring offrame cells 802 to converge at a link 820 between two adjacent framecells. The diverging and converging branches can form an eye-shapedmouth 810 that provides a proximal opening into the interior channel812. More particularly, the negative space between the two arcuatebranches can provide the mouth 810. Likewise, another mouth can bedefined between branches of the stem 602 on an opposite side of thearrestor structure. The other mouth can be separated from theillustrated mouth 810 by the branches, but can open into the sameinterior channel 812. Accordingly, the mouths of the clot arrestor 108provide ports through which clots can enter into and be captured by theexpandable frame 604.

Referring to FIG. 9, a side view of a clot arrestor is shown inaccordance with an embodiment. In the side view, the division betweenthe expandable frame 604 distal to the proximal ring end 803 and thestem 602 proximal to the proximal ring end 803 is seen. The interiorchannel 812 is the volume within the expandable frame 604. The stem 602extends proximally from the expandable frame 604 to the joint 606 at theproximal stem end 804, which joins the clot arrestor 108 to the supportwire 106. The branches of the stem 602 can bifurcate to connect todifferent proximal ring ends 803. Furthermore, the branches form themouth 810, which in the side view, has a mouth plane 902. The mouthplane 902 is the plane containing the negative space between thebranches that define the mouth 810, as described above. In anembodiment, the mouth plane 902 extends transverse to the support wire106. For example, whereas the support wire 106 includes the wire axisextending in the longitudinal direction, the mouth plane 902 may bearranged oblique to the wire axis, neither parallel nor perpendicular tothe wire.

The angle of the mouth plane 902 relative to the wire axis 402, e.g.,the oblique angle, can promote clot capture. For example, by angling themouth plane 902 it can provide a laterally directed opening throughwhich a clot can more easily pass. The oblique angle is one factoraffecting a size of the gap 704 between adjacent expandable frames 604.As described above, the size can impact the type of clot that iscaptured and how easily the clot is captured. For example, the angledmouth plane 902 can provide a more generous lead-in to the interiorchannel 812 to allow hard clots to roll more easily into the interiorchannel 812.

Referring to FIG. 10, a perspective view of a clot arrestor is shown inaccordance with an embodiment. As described above, the clot arrestors108 of the mechanical thrombectomy device 100 can have variedgeometries. In an embodiment, one or more of the expandable frames 604includes several struts 230 extending distal to the ring of frame cells802. The struts 230 can extend distally from an the distal edge of thering of frame cells 802. For example, the struts 230 can extend from anapex 1004 or a trough 1006 of the cell pattern at the distal edge. Thestruts 230 can bifurcate, as shown, to extend to several terminal endsat the distal frame end 706. Alternatively, the struts 230 may beunitary segments, e.g., straight strut protrusions that have a singleproximal end at the ring of frame cells 802 and a single distal end atthe distal frame end 706.

Referring to FIG. 11, a perspective view of a filter mounted on a clotarrestor is shown in accordance with embodiment. The mechanicalthrombectomy device 100 can include a filter 232 to capture clots thatpass distal to the expandable frames 604. In an embodiment, the filter232 is coupled to the ring of frame cells 802. For example, the filter232 can be mounted on the struts 230 that extend distally from the ringof frame cells 802. The filter 232 can have a distally converginggeometry. More particularly, the filter 232 can extend distally from aproximal filter end 1102 to a distal filter end 1104, and the proximalfilter end 1102 can have a larger transverse dimension than the distalfilter end 1104. The converging geometry can form a closed structure totraverse a lumen of the blood vessel 502 and capture any clots orportions of clots that pass distal to the expandable frames 604.

In an embodiment, the filter 232 includes a web or a mesh structure. Forexample, the filter 232 can be formed from a polymer or metal filamentthat is woven into a web or braided into a mesh having adistally-converging structure, such as a conical shape. The web or meshcan have a porosity that allows blood to pass, but captures clots orportions of clots that flow distal to the expandable frames 604. In anembodiment, the web or mesh is formed from a shape-memory material, suchas a nickel titanium alloy, however, the filter 232 may alternatively beformed from another material or metal, such as stainless steel.

The filter 232 may be formed from a thin sheet of material having apredetermined porosity. For example, the filter 232 may be formed from apolymer film having one or more holes formed through the film to permitblood flow. The filter 232 can be freely suspended at the proximalfilter end 1102. More particularly, there may be no internal framing tosupport the filter 232. Alternatively, the filter 232 can be supportedby one or more of the struts 230 extending distally from the expandableframe 604. In an embodiment, the struts 230 converge to a point (FIG.16). The freely suspended and/or internally supported filter 232 cancollapse during device delivery and expand within the target anatomy toprotect against the distal migration of clots.

The clot arrestor 108 can include a coil tip 1108. The coil tip 1108 canextend distally from the filter 232. The coil tip 1108 can be flexibleand atraumatic to the vessel wall 504. The coil tip 1108 can beradiopaque to provide improved visibility of the distal end of the clotarrestor 108. For example, the coil tip 1108 can be formed fromstainless steel, platinum-iridium, or another radiopaque metal ormaterial that is visible under fluoroscopy. In an embodiment, the coiltip 1108 is joined to the filter 232 and/or struts 230 of the expandableframe 604 by a mechanical, thermal, or adhesive joint. For example, thejoint can be an adhesive joint, which bonds the filter 232 to the coiltip 1108.

Whereas the filter 232 is shown as being a portion of the distalmostclot arrestor 108 (e.g., FIG. 2), it will be appreciated that any of theclot arrestors 108 of the mechanical thrombectomy device 100 can includea respective filter 232. Furthermore, any of the clot arrestors 108(proximalmost, medial, distalmost, etc.) can have distal ends thatconverge to respective distal tips 1106. More particularly, any and allof the expandable frames 604 can be enclosed at their distal ends toprovide a cage-like or filter-like structure that captures distallymoving clots. As with any of the clot arrestor structures describedherein, the distal geometry of the clot arrestors can be the same ordifferent for each clot arrestor relative to another clot arrestor.

Referring to FIG. 12, a pictorial view of a mechanical thrombectomydevice deployed in a curved vessel is shown in accordance withembodiment. The view provides a visual depiction of an advantage of theeccentrically supported expandable frames 604 and undulating supportwire 106, as described above. When the mechanical thrombectomy device100 is deployed in the blood vessel 502, each clot arrestor 108 can beattached to the support wire 106 at a joint 606 that has a stemextending from the joint with a different clocking, relative to thecentral axis 510 of the blood vessel 502. For example, in the embodimentshown, the mechanical thrombectomy device 100 can have four clotarrestors 108, each with respective joints 606 and stems having clockingthat differs by 90-degrees relative to an adjacent stem. Moreparticularly, the proximalmost clot arrestor 108 can have a stem at azero-degree position relative to the central axis 510 (at a bottomposition of the vessel wall 504), a second clot arrestor 210 adjacent tothe proximalmost clot arrestor 108 can have a joint 606 at a 90-degreeposition (measured counterclockwise about the central axis 510), a thirdclot arrestor 218 adjacent to the second clot arrestor 210 can have astem at a 180-degree position, and a distalmost clot arrestor 108adjacent to the third clot arrestor 218 can have a stem at a 270-degreeposition. As described above, the distal segment 304 of the support wire106 can undulate or spiral along and/or about the central axis 510 toconnect to the clot arrestors 108 at the joints 606. More particularly,the support wire 106 can press against the vessel wall 504 at each ofthe joint locations at alternately clocked locations relative to thecentral axis 510. Accordingly, the support wire 106 can extend throughthe expandable frames 604 offset from the central axis 510 of the bloodvessel 502. The offset location opens the central lumen of the bloodvessel 502 and the interior channels 812 of the expandable frames 604 toallow clots to move through the gaps 704 between clot arrestors 108 intothe interior channels 812 for capture.

Referring to FIG. 13, a pictorial view of a mechanical thrombectomydevice being retracted around a bend in a tortuous blood vessel is shownin accordance with an embodiment. The view provides a visual depictionof an advantage of the independently mounted clot arrestors 108, asdescribed above. The expandable frames 604 are connected to the supportwire 106, but are not directly coupled to each other. Thus, theindependently supported clot arrestors 108 are afforded a degree offreedom relative to each other, which leads to localized deformation ofindividual expandable frames 604 without global deformation of one ormore other expandable frames 604. That is, the deformation of oneexpandable frame 604 does not necessarily impact the other expandableframes 604.

In an embodiment, when the mechanical thrombectomy device 100 isdeployed into a tortuous blood vessel 502, one or more of the clotarrestors 108 may be retracted over a bend in the vessel. Moreparticularly, the support wire 106 is retracted through the blood vessel502 to retrieve the clot arrestors 108 (and any clots captured by theclot arrestors). Retraction of the support wire 106 can cause adeforming load 702 to be applied to one of the expandable frames 604. Asdescribed above, the deforming load 702 can have a radial component insome cases, and in the case of retracting over the bend, the deformingload 702 can also have an axial component that causes the expandableframe 604 located at the bend to stretch. More particularly, the tensioncaused by a proximal load applied to the joint 606 of the deformed clotarrestor 108 and a distal load applied by drag against the vessel wall504 can stretch the clot arrestor 108, as shown in FIG. 13. Thedeforming load 702 can cause the stretched expandable frames 604 tolengthen and, concomitantly, to reduce in diameter. As a result of thereducing diameter, the expandable frame 604 can lose apposition with thevessel wall 504. The other clot arrestors 108, however, areindependently mounted on the support wire 106 and can therefore remainunstretched despite the stretching of the clot arrestor 108 at the bend.The other clot arrestors 108, accordingly, do not lose apposition withthe vessel wall 504. Accordingly, deformation of the clot arrestors 108is localized (and minimized) to the clot arrestor 108 at the bend, whileensuring 802 that the blood vessel 502 proximal and distal to the bendremains protected by adjacent clot arrestors 108. As a result, any clot1302 that is force out of the stretched clot arrestor 108 or whichbreaks away and flows downstream within the vessel lumen can be capturedby an adjacent clot arrestor 108. A likelihood of capturing an entireclot 1302 and retrieving the thrombus from the target anatomy istherefore increased by the independently mounted clot arrestors 108.

Referring to FIG. 14, a flowchart of a method of manufacturing amechanical thrombectomy device is shown in accordance with anembodiment. The method described below is provided by way of example,and those skilled in the art would understand that such a method couldbe performed using alternative and/or additional manufacturingoperations to provide the mechanical thrombectomy device 100 describedabove.

At operation 1402, the support wire 106 is formed. In an embodiment, thesupport wire 106 is formed by grinding the a wire, e.g., a shape memoryalloy wire, to form a distal segment 304 that transitions to a proximalsegment 302 at the first location 209. As described above, the supportwire 106 can include several transitions to provide a wire that tapersin a continuous or step-wise fashion from the proximal wire end 110 tothe distal wire end 112. For example, the distal segment 304 can have asmaller diameter than the proximal segment 302. Accordingly, the supportwire 106 can have a stiffness profile that decreases in the distaldirection.

In an embodiment, rather than (or in addition to) grinding the supportwire 106, the support wire 106 can be formed from several wire segmentsthat are joined at discrete locations. The wire segments can be joinedusing mechanical, thermal, or adhesive joints 606. A distal wire segmentcan have a smaller diameter than a proximal wire segment to provide thedecreasing stiffness profile in the distal direction.

At operation 1404, a first clot arrestor 202 is mounted on the supportwire 106 at the first location 209. The first clot arrestor 202 can beattached to the support wire 106 by a mechanical, thermal, or adhesivejoint 606, such as the crimped marker band embedded in an adhesive bond,as described above. When attaching the first clot arrestor 202, the clotarrestor 108 can be oriented such that the stem 602 of the first clotarrestor 202 extends from the support wire 106 at a firstcircumferential location, e.g., a first clocking, relative to the wireaxis 402. The clocking can cause the first clot arrestor 202 to have aradial plane that extends through the wire axis 402 and the arrestoraxis 416 in a first radial direction.

At operation 1406, a second clot arrestor 210 is mounted on the supportwire 106 at a second location 217. The second clot arrestor 210 can beattached to the support wire 106 by a mechanical, thermal, or adhesivejoint 606, such as the crimped marker band embedded in an adhesive bond,as described above. The second location 217 can be longitudinally offsetfrom the first location 209, and may be distal to or proximal to theexpandable frame 604 of the first clot arrestor 202. When attaching thesecond clot arrestor 210, the clot arrestor 108 can be oriented suchthat the stem 602 of the second clot arrestor 210 extends from thesupport wire 106 at a second circumferential location, e.g., a secondclocking, different than the first circumferential location. Theclocking can cause the second clot arrestor 210 to have a radial planethat extends through the wire axis 402 and the arrestor axis 416 in asecond radial direction that is circumferentially offset from the firstradial direction. Accordingly the first and second clot arrestors 202,210 can be independently and eccentrically mounted on the support wire106. Furthermore, the expandable frames 604 can be non-concentricallysupported on the support wire 106 relative to each other.

At operation 1408, a radiopaque marker 310 is mounted on the supportwire 106 at the first location 209 and/or the second location 217. Theradiopaque marker 310 can mechanically join the stem 602 of theexpandable frame 604 to the support wire 106. For example, theradiopaque marker 310 can be a marker band that is crimped around thestem 602 and the support wire 106. Alternatively, the radiopaque marker310 can be a radiopaque particle, ink, or other structure that is joinedto the support wire 106 by an adhesive to provide visibility of thejoint 606 for positional feedback to an operator.

Referring to FIG. 15, a flowchart of a method of removing a clot from ablood vessel using a mechanical thrombectomy device is shown inaccordance with an embodiment. At operation 1502, a mechanicalthrombectomy device 100 is introduced into a blood vessel 502 containinga clot 1302. Initially, a guide wire can be traversed through the bloodvessel 502 into a targeted area in a narrow vasculature that is at leastpartially blocked by the clot 1302. A microcatheter can be tracked overthe guidewire such that a distal end of the microcatheter is locateddistal to the clot 1302. The guidewire can be retracted and removed fromthe microcatheter when the microcatheter is in place. The mechanicalthrombectomy device 100 can then be advanced through a lumen of themicrocatheter until the distal tip 1106 of the mechanical thrombectomydevice 100 is located near or distal to the distal end of themicrocatheter. When the mechanical thrombectomy device 100 is introducedinto the blood vessel 502, the microcatheter can maintain the clotarrestors 108 in a constrained configuration. That is, the microcatheterlumen may have a smaller diameter than the expanded clot arrestors 108,and thus, the expandable frames 604 can be introduced into the bloodvessel 502 through the microcatheter in an unexpanded state.

At operation 1504, the clot arrestors 108 are deployed. Forward pressurecan be placed on the support wire 106 of the mechanical thrombectomydevice 100 while retracting the microcatheter to cause the clotarrestors 108 to deploy from the distal end of the microcatheter intoapposition with the vessel wall 504 of the blood vessel 502. Moreparticularly, the expandable frames 604 can transition into an expandedstate (FIG. 1). In the expanded state, the expandable frames 604 apposethe vessel wall 504. The expandable frames 604 are eccentricallysupported on the support wire 106, and thus, when the expandable frames604 are deformed into a concentric arrangement within the vessel (FIG.12), the expandable frames 604 press against the vessel wall 504 indifferent transverse directions. The non-concentrically supportedexpandable frames 604, when biased into alignment, also cause thesupport wire 106 to be biased off-center and toward the vessel wall 504.More particularly, the support wire 106 extends through the blood vessel502 offset from the central axis 510 of the blood vessel 502.

After expanding the clot arrestors 108, the mechanical thrombectomydevice 100 may be left in place for several minutes to allow theexpandable frames 604 to engage the clot 1302. At operation 1506, thesupport wire 106 can then be pulled to retract the mechanicalthrombectomy device 100 to further engage, arrest, or capture the clot1302 with the expandable frames 604. The support wire 106 can be pulleduntil the clot arrestors 108, and the captured clot 1302, are removedfrom the target vasculature.

Referring to FIG. 16, a plan view of a distal portion of a mechanicalthrombectomy device having several clot arrestors is shown in accordancewith an embodiment. The distal working region 104 of the mechanicalthrombectomy device 100 can include several features that areinterchangeable with the embodiments described above. Such features arenot repeated with respect to FIG. 16 in the interest of brevity.

In an embodiment, the distal working region 104 includes several clotarrestors 108 having expandable frames 604 arranged sequentially in thelongitudinal direction. For example, the second expandable frame 212 canbe distal to the first expandable frame 204. Similarly, the thirdexpandable frame 220 can be distal to the second expandable frame 212.In the embodiment illustrated in FIG. 2, the clot arrestors 108 arearranged in a non-overlapping fashion, with each joint 606 of a clotarrestor 108 being located distal to an immediately proximal clotarrestor 108. As shown in FIG. 16, the clot arrestors 108 may, however,be at least partly overlapping in the longitudinal direction. Forexample, the second clot arrestor 210 can include a second stem 214 thatis coupled to the support wire 106 at a location that is proximal to thedistal frame end 706 of the first expandable frame 204. Moreparticularly, the second stem 214 can be attached to the support wire106 at the second joint 216, which is proximal to the first expandableframe 204.

The overlapping clot arrestors 108 can be facilitated by the elongatedstems 602 that extend proximally from a more distal expandable frame 604to the support wire 106 at a location proximal to a more proximalexpandable frame 604. The elongated stem 602 can provide increasedflexibility and movement of the expandable frame 604 relative to thesupport wire 106. Accordingly, although the expandable frames 604 areshown as being concentrically arranged along the support wire 106, itwill be appreciated that the expandable frames 604 could hinge outwardat the joints 606 to cause the expandable frames 604 to benon-concentrically (and eccentrically) supported on the support wire 106(FIG. 17).

In addition to making the expandable frames 604 more resilient andflexible about the support wire 106, connecting the expandable frames604 at joints 606 that are outside of the interior channel 812 of anadjacent expandable frame 604 can contribute to optimal packing ratio ofthe mechanical thrombectomy device 100. As described above, by placingthe joints 606 at locations along the support wire 106 that are notradially inward from the ring of frame cells 802 can allow the ring offrame cells 802 can be compacted to a smaller dimension during delivery.Thus, placement of the joints 606 proximal to the expandable frames 604can improve deliverability of the device.

Still referring to FIG. 16, one or more of the clot arrestors 108 of themechanical thrombectomy device 100 can have enclosed distal ends. Forexample, the third clot arrestor 218 (the distalmost clot arrestor) caninclude several struts 230 protruding distally from the ring of framecells 802. The struts 230 can converge at the distal tip 1106 to form anenclosed cage-like structure. More particularly, the cage-like structureformed from struts 230 defines an outline of a funnel or conical shapethat can allow blood flow but can also provide some resistance to thedistal flow of the clot 1302 through the blood vessel 502.

Referring to FIG. 17, a pictorial view of a mechanical thrombectomydevice including a support wire having one or more inflections is shownin accordance with an embodiment. The undulating and/or spiraling distalsegment 304 of the support wire 106 can include one or more inflections1702. Each inflection 1702 can be a change in a curvature of the supportwire 106 along the wire axis 402 in the distal direction. Theinflections 1702 can coincide with locations at which the clot arrestors108 are mounted on the support wire 106. For example, an undulation maybe a peak along which the first location 209 is located. The firstlocation 209 can be the location at which the first joint 208 connectsthe first clot arrestor 202 to the support wire 106. Similarly, anundulation may be a trough 1006, immediately distal to the peak, alongwhich the second location 217 is located. The second location 217 can bethe location at which the second joint 216 connects the second clotarrestor 210 to the support wire 106.

The inflections 1702 along the support wire 106 can be caused by theinteraction between the clot arrestors 108 and the vessel wall 504. Forexample, the spiraling path of the support wire 106 described above canpass through the joints 606, and thus, the inflections 1702 may becaused by the support wire 106 taking a particular shape to extend fromone joint 606 to another. Alternatively, the inflections 1702 may becaused directly by the clot arrestors 108 themselves. For example, theclot arrestors 108 may have a stem hole 1704 (FIG. 8) passing throughthe stem 602, e.g., near the proximal stem end 804. The support wire 106may be threaded through the stem hole 1704 (FIG. 9), and in doing so, anangle may be naturally created between the stem 602 at the stem hole1704 and the support wire 106 at the stem hole 1704. Furthermore, whenthe joint 606 is formed by crimping a marker band around the supportwire 106 and the stem 602, the joint 606 can cause a localized bendingmoment in the support wire 106 at the stem hole 1704. The bending momentcan produce a bend, which causes the inflection 1702 to be located atthe joint 606. Accordingly, the mechanical thrombectomy device 100 canhave a support wire 106 which, when deployed in free space or within theblood vessel 502, has an inflection 1702 for each of the clot arrestors108 mounted on the distal segment 304.

Referring to FIG. 18, a plan view of a distal portion of a mechanicalthrombectomy device having several clot arrestors deployed in free spaceis shown in accordance with an embodiment. The mechanical thrombectomydevice 100 includes several clot arrestors 108 mounted on the supportwire 106 and having respective expandable frames 604. For example, clotarrestors 108 can include the first clot arrestor 202 and the secondclot arrestor 210 independently mounted on the support wire 106. Themechanical thrombectomy device 100 is shown deployed in free space 1800,e.g., unconstrained by any surrounding surfaces, and thus, theexpandable frames 604 of the clot arrestors 108 are in a non-concentricrelationship with each other.

In an embodiment, the second clot arrestor 210 is a distalmost clotarrestor 1802. The distalmost clot arrestor 1802 can have the secondexpandable frame 212, and as described above, the expandable frame mayinclude a ring of frame cells. As described with respect to FIG. 11above, the ring of frame cells can support a filter (not shown) tocapture debris. The filter can be mounted on a distal end of thedistalmost clot arrestor 1802, and can include a mesh or web structure.The web structure may have a denser surface area than the secondexpandable frame 212, and thus, debris can become caught in the filterwhen flowing downstream within the blood vessel 502.

One or more of the clot arrestors 108 of the mechanical thrombectomydevice 100 can have segmented expandable frames. In an embodiment, thedistalmost clot arrestor 1802 has a segmented body 1804. Moreparticularly, the expandable frame can be segmented such that thesegmented body 1804 has a proximal frame segment 1806 and a distal framesegment 1808. The frame segments can be connected at a hinge 1810, andmay be separated from each other at all locations other than the hinge1810 by a segment gap 1812. The structure and function of the segmentedexpandable frame 604 is described further below.

Referring to FIG. 19, a plan view of a distal portion of a mechanicalthrombectomy device having several clot arrestors deployed in a bloodvessel is shown in accordance with an embodiment. When the mechanicalthrombectomy device 100 is deployed in the blood vessel 502 with theexpandable frames 604 apposed to the vessel wall 504 (vessel wall notshown) the expandable frames 604 are forced into a concentricrelationship with each other. As in the embodiments described above,when the mechanical thrombectomy device 100 is deployed in the bloodvessel 502 with the expandable frames 604 apposed to the vessel wall504, the support wire 106 can be forced to undulate along the vesselwall 504 offset from a central axis of the blood vessel 502. Forexample, an average amount of curvature of the support wire 106 per unitof axial length can be higher when the expandable frames 604 are forcedinto the concentric relationship than when the expandable frames 604 arein the non-concentric relationship in free space 1800.

In an embodiment, the clot arrestors 108 align with each otherconcentrically along the vessel wall 504. The expandable frames 604 ofthe clot arrestors 108 can conform closely to each other. Moreparticularly, a distance between adjacent expandable frames 604 (orframe segments of a same expandable frame 604) may be minimized. Asdescribed above, the first clot arrestor 202 can have the distal frameend 706 and the second clot arrestor 210 can have the proximal frame end708. The frame ends can be separated by the gap 704. The distal frameend 706 can conform to the proximal frame end 708 such that the gap 704is minimized. More particularly, the gap 704 between the distal frameend 706 in the proximal frame end 708 may be less than 10 mm at one ormore locations around a circumference of the vessel wall 504. Forexample, the gap 704 between the frame apices at the distal frame end706 and the mouth at the proximal frame end 708 may be in a range of1-10 mm, e.g., 1-5 mm.

A contour of the distal frame end 706 can have a same shape, extendparallel to, and/or conform to a contour of the proximal frame end 708.Here, the contour of the frame ends is defined by a profile or shape ofan imaginary spline passing through the expandable frame 604 at therespective end. For example, the contour of the distal frame end 706 maybe defined by an imaginary spline extending through a distalmost pointof each of the distal cells (e.g., the cell apices) making up the firstclot arrestor 202. Similarly, the contour of the proximal frame end 708may be defined by an imaginary spline extending through the strutsdefining a mouth of the second clot arrestor 210. As shown, in profile,the contours can closely match or conform to each other. Moreparticularly, the first clot arrestor 202 may be adjacent to the secondclot arrestor 210 without the clot arrestors actually touching. The clotarrestors 108 can therefore match or conform to one another toapproximate a continuous cylindrical body, even though there may be thegap 704 separating the segments of the body.

Closely positioning the clot arrestors 108 and/or segments of the clotarrestors 108 can maximize the frame surface area that can engage clotsalong the vessel wall 504. Consistent with the description above,however, it may be beneficial to provide a path for hard clots to moveinward from the vessel wall 504 into the lumen of the clot arrestors. Inan embodiment, struts making up the cells at the distal frame end 706 ofthe first clot arrestor 202 can flex radially inward. More particularly,the frame cells can be flexible enough to allow a hard clot to pressagainst and deform the distal frame end 706 radially inward. The distalend of the clot arrestor 108 can flap inward to allow the hard clot topass into the lumen of clot arrestor 108. Accordingly, by minimizing anaxial distance between adjacent clot arrestors 108, an overall structureis provided that can effectively engage soft clots while allowing hardclots to be captured within the clot arrestors 108.

Referring to FIG. 20, a perspective view of a distalmost clot arrestorof a mechanical thrombectomy device is shown in accordance with anembodiment. The segmented body 1804 of the distalmost clot arrestor 1802can include frame segments that conform closely to each other. Forexample, the proximal frame segment 1806 can have a distal segment end2002 that conforms closely to a proximal segment end 2004 of the distalframe segment 1808. Terminology and function of adjacent frame segmentscan be similar to the description of adjacent clot arrestors 108provided above. More particularly, the distal segment end 2002 can beseparated from the proximal segment end 2004 by a segment gap 1812,which may in effect be similar to the gap 704 between the distal frameend 706 and the proximal frame end 708. The segment gap 1812 canseparate the frame segments at all locations circumferentially aroundthe segmented body 1804 except at any locations where the hinge 1810connects the distal frame segment 1808 to the proximal frame segment1806.

In perspective, it is apparent that the hinge 1810 may be provided by aconnection point between a tail portion 2008 of the distal frame segment1808 and a ring of frame cells at a distal end of the proximal framesegment 1806. The frame segments may be integrally formed, e.g., cutfrom a same piece of metal tubing, and thus the hinge 1810 can be aconnector, link, or other connecting element between the distal framesegment 1808 of the proximal frame segment 1806.

Referring to FIG. 21, a side pictorial view of several clot arrestorsdeployed in blood vessel is shown in accordance with an embodiment. Whenthe mechanical thrombectomy device 100 is deployed within the vessel,the expandable frames and frame segments can concentrically align witheach other under the inward pressure provided by the vessel wall 504. Ina state in which no axial load is applied to the expandable frames 604through the support wire 106, the gap 704 between adjacent clotarrestors 108 and the segment gap 1812 between frame segments may beminimal. For example, the adjacent profiles of the frames and framesegments can conform to each other and be separated by gaps 704, 1812 ofbetween 1-10 mm, e.g. 1-5 mm. The clot arrestors 108 can therefore actas a continuous cylindrical structure that uniformly contacts the vesselwall 504 to engage clots.

Referring to FIG. 22, a side pictorial view of several clot arrestorsdeployed in a blood vessel is shown in accordance with an embodiment.When a deforming load is applied to the support wire 106, e.g., an axialload to retract the support wire 106 and the clot arrestors 108 throughthe blood vessel 502, the deforming load can cause the frame segments ofthe segmented body 1804 and/or the independent clot arrestors 108 totilt relative to each other. More particularly, the gap 704 betweenadjacent clot arrestors 108 and/or the segment gap 1812 between adjacentframe segments can widen. The tilting of the independently mountedand/or hinged structures can result from the flexibility provided by thejoints along the support wire 106 and or the hinge 1810 between framesegments.

Rather than causing the individual frames and frame segments to stretchand reduce in diameter, the axial load is distributed through the framestructures in such a way that the individual frames and frame segmentsremain cylindrical in form but pivot outward relative to each other.More particularly, the segments can tilt, but may not collapse inprofile. The structure segments can splay outward to press against clotsin the blood vessel 502. The tilting action may be especially beneficialaround tortuous bends. By limiting axial stretching of the structuresegments, contact between the structure segments in the vessel wall 504can be maintained when the mechanical thrombectomy device 100 isdeployed around a bend in a tortuous vessel. Thus, the structuresegments can maintain contact with clots along the vessel wall 504 tobetter capture the clots.

In addition to engaging clots around vessel bands, the tilting actionprovided by the hinged frame segments can provide openings for hardclots to enter into the lumen of the clot arrestors 108. Moreparticularly, the widening gaps between structure segments can allow forhard clots to pass radially inward into the lumen. From the descriptionabove, it will be appreciated that the mechanical thrombectomy device100 can incorporate one or more clot arrestors 108 having the segmentedbody 1804 to allow the frame segments to be retracted through the bloodvessel 502 with minimal stretching and such that the frame segmentspress outward against soft clots while also opening to capture hardclots.

Referring again to FIG. 20, several frame markers 2010 can be mounted onone or more of the expandable frames 604. The frame markers 2010 canimprove visibility of the expandable frame 604 on which they aremounted. More particularly, the frame markers 2010 can provide visualfeedback under fluoroscopy to allow a user to note a position of theclot arrestor 108 within the target anatomy. The frame markers 2010 maytherefore be fabricated from a radiopaque material, such as platinumiridium. The frame markers 2010 can be positioned along a distalmostring 802 of frame cells of the mechanical thrombectomy device 100. In anembodiment, frame markers 2010 are mounted on one or more of the strutsat a distal end of each clot arrestor 108 of the mechanical thrombectomydevice 100.

Referring to FIG. 23, a perspective view of a frame marker is shown inaccordance with an embodiment. The radiopaque material of the framemarker 2010 can be plated on the expandable frame 604. Alternatively,the frame marker 2010 may be formed into a band that is crimped onto theexpandable frame 604. In an embodiment, the frame marker 2010 includes amarker coil 2400. The marker coil 2400 can be formed from a radiopaquewire that is coiled or wrapped around a strut of the expandable frame604. For example, the wire may be wrapped in 5-10 turns about a strut ofthe distalmost clot arrestor 1802. Solder may be applied around themarker coil 2400 to secure the coil to the strut. Furthermore, as shown,the solder can form bulbous features at each end of the coil to providean atraumatic surface that does not damage the vessel wall 504 duringuse.

Referring to FIG. 24, a plan view of a radiopaque coil mounted on asupport wire of a mechanical thrombectomy device is shown in accordancewith an embodiment. The mechanical thrombectomy device 100 may, inaddition to the frame markers 2010 on the distalmost clot arrestor 1802,include a radiopaque coil 2400 mounted on the support wire 106 proximalto the clot arrestors 108. The radiopaque coil 2400 can provide visualfeedback under fluoroscopy to allow the user to note a position of theproximal region of the mechanical thrombectomy device 100. As describedabove, the support wire 106 can include the distal segment 304supporting the clot arrestors 108, and the proximal segment 302 locatedproximal to the distal segment 304. More particularly, the proximalsegment 302 can be proximal to the clot arrestors 108, and the distalsegment 304 can extend through the clot arrestors 108 (and at least oneof the clot arrestors 108 can be mounted on the distal segment 304).

In an embodiment, the proximal segment 302 and the distal segment 304are coupled to the radiopaque coil 2400. By way of example, the proximalsegment 302 can have a distal end that connects to the radiopaque coil2400 at a coil joint 2402. The distal segment 304 may also be connectedto the radiopaque coil 2400 at the coil joint 2402. For example, asolder bond may be formed between the radiopaque coil 2400, the proximalsegment 302, and the distal segment 304, at the coil joint 2402. Thedistal segment 304 may extend through the radiopaque coil 2400 in thedistal direction. In an embodiment, a clot arrestor 108 connects to thedistal segment 304 at the first joint 208, and the distal segment 304extends distally to a connection point with one or more additional clotarrestors 108 at joints distal to the first joint 208.

The radiopaque coil 2400 can enhance visibility of the mechanicalthrombectomy device 100, and can provide a more robust joint between theproximal segment 302 and the distal segment 304. Additional joints maybe formed along the coil. For example, a solder joint may be formedbetween the radiopaque coil 2400 and the proximal segment 302 or thedistal segment 304 at a medial location of the radiopaque coil 2400and/or a distal end of the radiopaque coil 2400. As described above, theproximal segment 302 of the support wire 106 can have a larger diameterthan the distal segment 304 of the support wire 106.

A method of engaging a clot using the mechanical thrombectomy device 100as described with respect to FIGS. 18-24 can be the same or similar tothe method described with respect to FIG. 15 above. More particularly,the mechanical thrombectomy device 100 can be introduced into the bloodvessel 502 containing the clot. In the free state, the clot arrestors108 may naturally misalign into a non-concentric relationship with eachother, however, upon deploying the clot arrestors 108 in the bloodvessel 502, the expandable frames 604 of the clot arrestors 108 canappose the vessel wall 504, and the vessel wall can supply aconstraining force that forces the expandable frames 604 into aconcentric relationship with each other. The mechanical thrombectomydevice 100 may then be retracted, e.g., by pulling on the support wire106, to engage the clot with the expandable frames 604. Retraction ofthe mechanical thrombectomy device 100 can cause the independent clotarrestors and/or the frame segments of the segmented body 1804 to tiltrelative to each other. The tilting action may limit axial stretching ofthe individual bodies and allow the structural segments to press outwardagainst clots and to open along widening gaps that receive hard clotsinto the lumen of the clot arrestors 108. Accordingly, the mechanicalthrombectomy device 100 can provide excellent clot engagement due tominimized stretching of the frame structure, and can also provideexcellent clot capture.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

What is claimed is:
 1. A mechanical thrombectomy device, comprising: asupport wire; and a plurality of clot arrestors having respectiveexpandable frames, wherein the plurality of clot arrestors areindependently mounted on the support wire such that the expandableframes are in a non-concentric relationship with each other when themechanical thrombectomy device is deployed in free space, and theexpandable frames are forced into a concentric relationship with eachother when the mechanical thrombectomy device is deployed in a bloodvessel with the expandable frames apposed to a vessel wall.
 2. Themechanical thrombectomy device of claim 1, wherein the plurality of clotarrestors includes a first clot arrestor proximal to a second clotarrestor, wherein the first clot arrestor has a distal frame end and thesecond clot arrestor has a proximal frame end, and wherein the distalframe end conforms to the proximal frame end.
 3. The mechanicalthrombectomy device of claim 2, wherein a gap between the distal frameend and the proximal frame end is less than 10 mm.
 4. The mechanicalthrombectomy device of claim 1, wherein a distalmost clot arrestorincludes a ring of frame cells, and further comprising a filter coupledto the ring of frame cells.
 5. The mechanical thrombectomy device ofclaim 1, wherein the support wire includes a proximal segment proximalto the plurality of clot arrestors, and a distal segment extendingthrough one or more of the plurality of clot arrestors, and furthercomprising a radiopaque coil mounted on the support wire, wherein theproximal segment and the distal segment are coupled to the radiopaquecoil.
 6. The mechanical thrombectomy device of claim 5, wherein theproximal segment of the support wire has a larger diameter than thedistal segment of the support wire.
 7. The mechanical thrombectomydevice of claim 1 further comprising a plurality of frame markersmounted on one or more of the expandable frames, wherein the pluralityof frame markers are radiopaque.
 8. The mechanical thrombectomy deviceof claim 1, wherein the support wire is forced to undulate along thevessel wall offset from a central axis of the blood vessel when themechanical thrombectomy device is deployed in the blood vessel with theexpandable frames apposed to the vessel wall.
 9. A mechanicalthrombectomy device, comprising: a support wire; a first clot arrestormounted on the support wire and having a first expandable frame; and asecond clot arrestor mounted on the support wire and having a secondexpandable frame, wherein the second expandable frame includes asegmented body having a proximal frame segment coupled to a distal framesegment at a hinge; wherein the expandable frames are in anon-concentric relationship with each other when the mechanicalthrombectomy device is deployed in free space, and the expandable framesare forced into a concentric relationship with each other when themechanical thrombectomy device is deployed in a blood vessel with theexpandable frames apposed to a vessel wall.
 10. The mechanicalthrombectomy device of claim 9, wherein the proximal frame segment has adistal segment end and the distal frame segment has a proximal segmentend, and wherein the distal segment end is separated from the proximalsegment end by a circumferential gap such that the distal frame segmentis coupled to the proximal frame segment only at the hinge.
 11. Themechanical thrombectomy device of claim 10, wherein, when a deformingload is applied to the support wire to retract the support wire throughthe blood vessel, the deforming load causes the frame segments of thesegmented body to tilt about the hinge such that the circumferential gapbetween the frame segments widens.
 12. The mechanical thrombectomydevice of claim 9, wherein the first clot arrestor is proximal to thesecond clot arrestor, wherein the first clot arrestor has a distal frameend and the second clot arrestor has a proximal frame end, and whereinthe distal frame end conforms to the proximal frame end.
 13. Themechanical thrombectomy device of claim 12, wherein a gap between thedistal frame end and the proximal frame end is less than 10 mm.
 14. Themechanical thrombectomy device of claim 9, wherein the second expandableframe includes a ring of frame cells, and further comprising a filtercoupled to the ring of frame cells.
 15. The mechanical thrombectomydevice of claim 9, wherein the support wire is forced to undulate alongthe vessel wall offset from a central axis of the blood vessel when themechanical thrombectomy device is deployed in the blood vessel with theexpandable frames apposed to the vessel wall.
 16. A method of removing aclot from a blood vessel, comprising: introducing a mechanicalthrombectomy device into the blood vessel containing the clot, whereinthe mechanical thrombectomy device includes a support wire and aplurality of clot arrestors including respective expandable frames,wherein the plurality of clot arrestors are independently mounted on thesupport wire such that the expandable frames are in a non-concentricrelationship with each other when the mechanical thrombectomy device isdeployed in free space; deploying the plurality of clot arrestors in theblood vessel to transition the expandable frames into apposition with avessel wall such that the expandable frames are forced into a concentricrelationship with each other; and retracting the mechanical thrombectomydevice to engage the clot with the expandable frames.
 17. The method ofclaim 16, wherein the plurality of clot arrestors includes a first clotarrestor proximal to a second clot arrestor, wherein the first clotarrestor has a distal frame end and the second clot arrestor has aproximal frame end, and wherein the distal frame end conforms to theproximal frame end.
 18. The method of claim 16, wherein a distalmostclot arrestor includes a ring of frame cells, and further comprising afilter coupled to the ring of frame cells.
 19. The method of claim 16,wherein the plurality of clot arrestors include a first clot arrestormounted on the support wire and having a first expandable frame, and asecond clot arrestor mounted on the support wire and having a secondexpandable frame, and wherein the second expandable frame includes asegmented body having a proximal frame segment coupled to a distal framesegment at a hinge.
 20. The method of claim 16, wherein the support wireis forced to undulate along the vessel wall offset from a central axisof the blood vessel when the mechanical thrombectomy device is deployedin the blood vessel with the expandable frames apposed to the vesselwall.